Apparatus for producing cooked products

ABSTRACT

A fried bakery product, such as a chemically leavened and extruded doughnut, is produced by apparatus which is arranged to first totally immerse a piece of dough for the fried product in a frying vessel containing an edible frying medium at a frying temperature wherein the edible frying medium is liquid and for a time sufficient to assure proper shaping of the dough piece. Thereafter, the dough piece, while partially immersed in the frying medium, is moved by a conveyor to an intermediate location of the frying vessel at which it is subjected to microwave energy from a microwave source concurrent with frying of the underside thereof. The fried product is completed by the provision of an inverting mechanism which turns the same in the frying medium. The resulting product has a number of improved characteristics including uniform crumb density and better physical properties and eating characteristics.

United States Patent [72] Inventors 2,491,687 12/1949 Nutt Appl. No.

Filed Patented Assignee This application Aug. 17, 1970, Ser. No.

APPARATUS FOR PRODUCING COOKED PRODUCTS 13 Claims, 5 Drawing Figs.

US. Cl...

References Cited UNITED STATES PATENTS o vaaaaavao 9440, v.- ,7

99/339, 99/1, 99/405, 99/407, 99/443 C, 99/DIG. 14, 219/1047, 219/1069Int. Cl A47j 37/12 Field of Search 219/1055, 10.57,10.47,10.69;99/1,86,94, 339, 353, 354,

404, 405, 406, 407, 443, DIG. 14, 100

Primary Examiner-Billy J. Wilhite Attorney-Amster & Rothstein ABSTRACT:A fried bakery product, such as a chemically leavened and extrudeddoughnut, is produced by apparatus which is arranged to first totallyimmerse a piece of dough for the fried product in a frying vesselcontaining an edible frying medium at a frying temperature wherein theedible frying medium is liquid and for a time sufficient to assureproper shaping of the dough piece. Thereafter, the dough piece, whilepartially immersed in the frying medium, is moved by a conveyor to anintermediate location of the frying vessel at which it is subjected tomicrowave energy from a microwave source concurrent with frying of theunderside thereof. The fried product is completed by the provision of aninverting mechanism which turns the same in the frying medium. Theresulting product has a number of improved characteristics includinguniform crumb density and better physical properties and eatingcharacteristics.

PATENTEB JAN? '1 I972 SHEET 2 OF 3 INVENTORS w M Mw 0 a mama mam JDAM eREA N a n rwwm m m0"? M u A Y R B APPARATUS FOR PRODUCING COOKEDPRODUCTS This is a division of US. application Ser. No. 519,255, filedJan. 7, 1966 in the name of Robert F. Schiffmann et al. for Method ofProducing Cooked Products and Apparatus Therefor now abandoned.

The present invention relates generally to the production of comestiblesand, in particular. to an improved apparatus for the production of friedcakes, such as doughnuts and the like.

The conventional method of cooking doughnuts requires that a cut andshaped piece of doughnut dough be dropped into hot fat in which itremains submerged for from 2 to 10 seconds, after which the piece willfloat to the surface with a portion thereof out of the fat. As isgenerally understood, this total immersion of the cut and shaped pieceof doughnut dough causes the formation of a shape-retention skin thereonwhich assures that the dough, after being cooked in the frying fat, willexpand properly. If the submersion is of too short a time, there is atendency for the dough when cooked to misshape, for example, to expandtoo much in the lateral direction, causing the final-product to appearflattened and ringy and to have an oversized hole in the center thereof.With the presence of an appropriate shape-retention skin, desirablelateral and height proportions will be established during expansion andusually the hole size will decrease and change the shape of thecontiguous wall into a star-shaped configuration. Commonly, such adoughnut is referred in the trade as a blooming doughnut."

If the total submergence period is too long, that is, in excess ofseconds, the shape-retention skin becomes a crust which willsignificantly reduce the expandability of the dough during the remainderof the frying. As long as the total submergence phase of the cookinglies between 2 and 10 seconds, the halfof the dough which floats abovethe level of the fat is still expandable within the shape-retentionskin. Although some doughnuts and other fried cake products are cookedcompletely by forcing the product to be submerged for the entire cookingtime, most doughnut products are cooked in two parts, that is, the lowerpart of the doughnut remaining below the surface of the fat after theinitial total submergence is fried for 40 to 60 seconds and then theunfinished doughnut is turned over so that the uncooked upper part thatwas floating above the surface of the fat is submerged. This secondphase of cooking again takes from 40 to 60 seconds for completion of thecooking process. This latter method of cooking is preferred even thoughit takes from 80 to 120 seconds as compared to 60 to 80 seconds fortotally submerged cooking because many favorable product characteristicscan be obtained. These characteristics include texture and thickness ofthe crust, texture and appearance of the crumb and shapingcharacteristics, such as the formation of a star-shaped hole in thedoughnut characteristic of the blooming doughnut. A most importantcharacteristic effected, however, is the size or volume of product perunit weight of dough used. The twopart cooking method can produce 50percent more volume per unit weight of dough than can be produced by thetotally submerged cooking method.

Even though the two-part cooking method is a distinct improvement overthe method in which the comestible is totally submerged, it has thedrawback of requiring up to two times the frying time and therefore, theuse of very large frying vessels and large quantities of fat to fillthem for high production. This is an important disadvantage since inmost commercial bakeries space is at a premium. Likewise of importanceis the fact that the chemical nature of fat and the conditions underwhich it is used require that it be consumed, that is, removed by theproduct, and replaced with fresh unused fat at a rate of not less thanpercent of the total fat capacity of the vessel for 7 hours ofproduction, otherwise fat oxidation products will accumulate toexcessive levels and be deleterious to the quality ofthe fried product.

In addition to the above drawbacks, the conventional cake fryingprocedures possess many other important disadvantages. The fried cakes,even when produced by the twopart frying method. do not have a specificvolume which approaches the theoretically available specific volume forthe specific dough employed, the cakes are not uniform in their physicalcharacteristics and appearances, close process control must be observed,and the conventional cake frying processes otherwise leave much to bedesired.

It is, therefore, a principal object of the present invention to providean improved apparatus for the production of comestibles.

Another object of the present invention is to provide an improvedapparatus for the cooking of dough in the production of fried cakes suchas doughnuts and the like.

Still another object ofthe present invention is to provide improvedequipment for the production of fried cakes in which the cooking time isgreatly reduced and the capacity of the related processing apparatus,relative to its size, is greatly increased.

A further object ofthe present invention is to provide an improvedapparatus for the production of fried cakes wherein the volume ofcooking oil employed in the apparatus relative to the oil consumption isgreatly reduced thereby reducing the production of undesirable oxidationproducts.

Still a further object of the present invention is to provide improvedfried cake cooking equipment wherein a maximum specific volume ofproduct is achieved in relationship to the dough being employed.

Another object of the 'present invention is to provide an improved friedcake cooking unit which requires a minimum of process control and doughproperty control and which efficiently produces cakes of uniform highquality, physical characteristics and appearance.

Still another object ofthe present invention is to provide apparatus ofthe above nature characterized by its reliability, flexibility,versatility and ease of operation.

In accordance with an illustrative embodiment demonstrating apparatusaspects of the present invention, there is provided apparatus forforming and frying bakery products comprising an elongated frying tankhaving an input section, an intermediate section and an output sectionwhich is adapted to contain a liquid cooking medium. Means are providedfor heating the cooking medium to a frying temperature. A conveyor isarranged within the tank for advancing partially submerged bakeryproducts to be fried along a conveyor path from the input sectionthrough the intermediate section and to the output section at aprescribed rate. A dough ring cutting and extruded device is arrangedover the input section of the frying tank and is adapted to dropsuccessive extruded dough pieces for the bakery product into the inputsection of the frying tank along the conveyor path. The conveyor isconstructed and arranged such that successive dough pieces are initiallytotally submerged in the cooking medium and then advanced toward theintermediate section in a partially submerged condition. A microwavegenerator including a cavity and an energy-outlet port is arranged tointroduce the microwave to the intermediate section of the frying tankand along the conveyor path such that successive partially submergeddough pieces are exposed to microwave energy from the microwavegenerator for a time determined by the prescribed rate and thedimensioning of the energy outlet port. A dough-piece-turning mechanismis arranged within the frying tank along the conveyor path and followingthe intermediate section for turning successive dough pieces afterexposure to the microwave energy and for delivering the turned doughpieces to the output section of the frying tank.

The above and other objects of the present invention will becomeapparent from a reading of the following description taken inconjunction with the accompanying drawing, wherein:

FIG. 1 is an exploded perspective, part fragmentary, view of anapparatus embodying the present invention;

FIG. 2 is a vertical longitudinal sectional view thereof;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2; and

FIG. 5 is a sectional view taken along line 5-5 of FIG. 2.

The present invention contemplates apparatus for producing a cookedproduct arranged to provide for the external application of heat to aside of an extruded piece of heat expandable dough to form a crustthereon while leaving another side thereof in a substantially uncrustedstate and a microwave generator for subjecting said partially cookedpiece of dough to a high-frequency electromagnetic field to heat saiddough internally and effect the expansion thereof. The present apparatusincludes an extruder which is charged with a dough batter containing achemical leavening agent and is arranged to form and extrude dough ringsdirectly above a cooking vessel containing a hot cooking oil at a pointtrailing the zone to which the high-frequency field is confined. Thevessel is provided with a conveyor for continuously advancing the doughpieces from a trailing to a leading section, the high-frequency fieldbeing confined to an intermediate section and means are provided forturning the dough pieces following the highfrequency zone to depositthem in the leading section in an inverted state. Confining thehigh-frequency or microwave field to the intermediate section of theconveyor assures the proper shaping of the dough through the formationof the shape-re- -tention skin in advance of subjecting the thenpartially immersed dough to the microwave field. The cooking oil ismaintained at a temperature ranging between 300 and 400 F. andadvantageously between 350 and 375 F. The dough piece is disposed in thetrailing or partial crusting section for a period between 1 and 20seconds, advantageously between 6 and 15 seconds to assure shaping bythe formation of a shape-retention skin before it is completelypositioned in the highfrequency zone wherein the dough piece ispartially submerged with its upper portion in an expandable state andits lower submerged portion in a crusted substantially unexpandablestate, such condition permitting the desired expansion and shaping ofthe dough piece in an optimum manner. The dough piece, in thehigh-frequency field hereinafter set forth, that is, for example, afrequency of 2,450 megacycles per second at a power of 1.6 kilowatts, isadvantageously exposed to the high-frequency field for'a period ofbetween 10 and 25 seconds, preferably between and seconds, and isremoved from the high-frequency zone and inverted in the hot oil in theleading zone where the cooking of the inverted piece of dough in the hotoil is completed for a period between 20 and 40 seconds, advantageouslybetween and seconds. The dough piece, to advantage, may also be exposedto the high-frequency field following the inversion of the expandeddough piece in the hot oil in the leading zone, for at least part of itspresence in the leading zone. As an alternative, the dough piece may beexpanded and its cooking completed while exposed to the high-frequencyfield and without inversion by exposing the floating dough piece to thehigh-frequency field for a period advantageously between 20 and 55seconds and preferably between 30 and seconds. During this latterperiod, it has been observed that the oil appears to be pumped over theupper face of the dough piece eventually to effect the cooking andcrusting thereof following its expansion. The frequency of theelectromagnetic field is that normally employed in dielectric heating,for example, between 915 and 2,450 megacycles per second and itsintensity and the time of exposure of the dough piece is sufficient toeffect the desired expansion of the dough and can be readily determinedby one skilled in the art, it being noted that the expansion of thedough piece in the high-frequency field is a function of the frequencyand intensity of the field and the time of exposure thereto.

Apparatus for practicing the present invention includes an elongatedvessel containing a cooking oil and means for heating the oil to apredetermined temperature. There are located in the cooking vesselconveying means for advancing the dough pieces and which includelongitudinally spaced transversely extending flights, and dough pieceinverting means including rotating paddles positioned between the endsof the conveyor. A perforated cage defining a high-frequency compartmentencloses at least an intermediate section of the cooking vessel trailingthe inverting means and confined passageways extend forwardly andrearwardly of the compartment, the high-frequency field being highlyattenuated in these passageways. The trailing passageway is providedwith a top opening at its trailing end with which registers the nozzleof a conventional dough ring forming extruding and cutting device. Ahigh-frequency generator is positioned in the compartment and isconnected to a suitable energy source.

Referring now to the drawings, reference numeral 10 generally designatesapparatus for practicing this new process which comprises an open toppedelongated tank or cooking vessel 11, a dough piece conveyor and flipperassembly 12, a high-frequency radiation confining housing or cage 13 anda high-frequency generator assembly 14. Tank 11 is formed of anysuitable metal and is of rectangular configuration including a bottomwall 16, end walls 17, and front and rear walls 18.

A heating element 19, in the form ofa metal sheathed resistance heater,is disposed in tank 11 and extends along bottom wall 16 and is providedwith end legs 20 extending upwardly along front wall 18 to a powercontrolling and temperature regulating box 21 (see FIG. 1). Control box21 is of conventional construction, controlling the electricalenergization of the heating element 19 in response to a thermostaticdevice to regulate the temperature of the cooking oil in tank 11 to anadjustable predetermined frying temperature. The control box 21 ispositioned forwardly of front wall 18 and is suitably mounted and isconnected to the heating element end legs 20 by short arms 22. Supportedin tank 11 immediately above heating element 19 and ofa width somewhatless than that of bottom wall 16 is a rectangular grid 23 (see FIG. 2),provided at opposite ends with transversely extending depending flanges24 which rest on the end borders of the bottom wall 16 to removablysupport grid 23. A transversely extending arcuate channel 26 is formedin grid 23 between the ends thereof.

The conveyor and flipper assembly 12 comprises a support frame 27 whichremovably rests in tank 11 and includes front and rear similar panels 28and 29 respectively, which are parallel and adjacent to front and rearwalls 18 of the tank. Each panel 28 and 29 includes a leading uppercorner 25 of small rectangular section which substantially rests on theupper edge of the leading end wall 17 of the tank, the main rectangularsection 30 having legs resting on tank bottom 16, with a leading edgethereof contiguous to the tank leading end wall 17, and a trailing edgecontiguous to the tank trailing end wall 17, and a top edge shortlyabove that of tank 11.

A horizontal drop plate 33 (see FIGS. 2 and 5) extends transverselybetween and is secured to opposite trailing ends of main sections 30between the top and bottom edges thereof, and an upwardly forwardlyinclined discharge ramp plate 34 is located between and is secured tothe upper leading parts of plates 28 and 29 and terminates at theleading sections 25.

Journaled in and extending between plates 28 and 29 are transverselyextending parallel leading, intermediate and trailing shafts 36, 37 and38, respectively, shafts 36 and 38 being disposed just below the levelof drop plate 33, trailing shaft 38 being located below the trailingedge of drop plate 33, and intermediate shaft 37 being above the levelof shafts 36 and 38. Affixed to shafts 36 and 38 are pairs ofsimilarsprocket wheels 39 which are spaced inwardly of the confronting faces ofplates 28 and 29, and affixed to the shaft 37 are sprocket wheels 40which are smaller than sprocket wheels 39 and are likewise spacedinwardly of support plates 28 and 29. A pair of transversely spacedparallel, longitudinal sprocket chains 41 are supported by and betweencorresponding sprocket wheels 39 and engage the upper teeth of sprocketwheels 40.

Supported by and between and depending from sprocket chains 41 areregularly longitudinally spaced parallel transversely extending flights42 which are advanced by sprocket chains 41 from the trailing sprocketwheels 39 along the upper face of drop plate 33, to the leading sprocketwheels 39 and then under, around and back to and around trailingsprocket wheels 39. A pair of perforated transversely extending flippingpaddles 43 are affixed to and project radially oppositely fromintermediate shaft 37 which is coaxial with arcuate channel 26, eachpaddle 43 being of somewhat less depth than the distance betweensuccessive flights 42, and being provided along its inner edge with aflange 44 projecting in the direction of rotation of the paddles 43.Sprocket wheels 39 and 40 are so dimensioned and related that with eachincrement advance of a flight 42 for a distance equal to that betweensuccessive flights 42, shaft 37 rotates 180 and the trailing flippingpaddle 43 receives a dough piece located in a pocket or cell between apair of adjacent flights 42 and inverts the dough piece and deposits itinto theadvancing pocket. It should be noted that the level of thecooking oil in the tank 12 is above that of the drop plate 33 preferablyby an amount about that of the height of the dough ring being cooked andat about the level of or slightly below the upper sections of flights42. A gear 46 is affixed to the rear end of the leading shaft 36.

A lower transversely extending shaft 47 is disposed below and trails thetrailing edge of ramp plate 34 and an upper transverse shaft 48 isdisposed adjacent to and in advance of the leading upper edge of rampplate 34. Shafts 47 and 48 are journaled to and between support plates28 and 29 and a plurality of axially spaced sprocket wheels 49 areaffixed to each of shafts 47 and 48, said sprocket wheels beinglongitudinally aligned. A sprocket chain 50 extends between and abouteach pair of longitudinally aligned sprocket wheels 49 and extends alongthe upper face of ramp plate 34, the trailing edges of the sprocketchains being shortly forward of the leading end run of flights 42. Agear 51 is affixed to the rear end of shaft 47 and is coupled to gear 46by a sprocket chain 52. Drive shaft 48 is driven in any suitable manner,such as by a suitably mounted adjustable speed drive motor 53 connectedto shaft 48. Motor 53 is driven to advance sprocket chains 50 andflights 42 along their upper runs. Sprocket wheels 49 on upper shaft 48are disposed directly above the upper edge of the tank leading end wall17 so that the conveyor defined by the sprocket chains 50 dischargesover the upper edge of leading end wall 17.

The cage 13 functions to direct and confine the highfrequency radiationfrom generator assembly 14 to a predetermined area of cooking tank 11,specifically between flipper shaft 37 and a section trailing shaft 38 oralternatively between shaft 36 and said trailing section, and tominimize external radiation. Cage 13 is formed ofa perforated metal, theopenings being large enough to permit the circulation of airtherethrough but sufficiently small to prevent the passage of thehigh-frequency heating radiation, and includes a lower main section 54which engages and houses cooking tank 11, a discharge section 56 forwardof and extending above main section 54, an intermediate section 57affording communication between the upper adjacent parts of sections 54and 56, and a high-frequency coupling section 58 extending above mainsection 54.

Main section 54 comprises a rectangular top wall 59 ofsubstantially thecorresponding horizontal dimensions of cooking tank 11, depending frontand rear walls 60 and 61 and vertical leading and trailing end walls 63and 64, respectively. Cage walls 60, 61, 63 and 64 extend substantiallyto the bottom of cooking tank 11 and engage the outside faces of the corresponding walls thereof and the cage top wall 59 is disposed above thecooking tank 11 at about or slightly above the level of the upper edgesof support plate sections 30. Formed in the trailing border of the cagetop wall 59, intermediate its front and rear edges is a circular doughpiece feed port 65 provided with an upstanding peripheral flange 66. Adough ring extruding and cutting device 67 of conventional constructioncoaxially registers with the port 65 and is synchronized with conveyorsights 42 in the known manner to drop a dough ring through port 65 intoan underlying pocket between successive flights 42, during eachincrement advance of the flights 42.

A rectangular opening 68 is formed in the cage top wall 59 forwardoffeed port 65 and extends for a short distance less than the width ofwall 59 and about to the leading end of the upper run of flights 42.Coupling section 58 is substantially hopper shaped, open at its top andbottom and registering with opening 68, and includes a vertical trailingwall 69 directed upwardly from the trailing edge of opening 68 andprovided at its upper border with transversely projecting coplanar wings70, and upwardly diverging front and rear walls 71, and a furwardlyupwardly inclined leading wall 72 terminating in a transverselyextending vertical flange 73. The upper edges of front and rear walls 71are provided with outwardly directed horizontal flanges which terminatein upwardly directed flanges 74. The upper border of wall ,69 andflanges 73 and 74 define a rectangular coupling frame 76. A removableperforated metal partition 77 is disposed in coupling section 58 andincludes a panel 78 inclined rearwardly downwardly from the upper edgeof the wall 72 and terminating in a depending skirt 79 disposed at aboutthe level of the opening 68 and substantially intermediate its leadingand trailing edges, partition 77 extending between sidewalls 71 anddefining therewith and with the rear wall 69 a high-frequency directingcompartment 80.

Discharge section 56 includes a rectangular base wall 81 projectingforwardly of the bottom edge of wall 63 substantially coplanar with thebottom of the cooking tank 11 and is provided with vertical front andrear walls 82 extending upwardly from corresponding .edges of base wall81 to a level above that of main section top wall 59. The upper edges ofthe walls 82 are joined by a horizontal top wall 83 which extendsrearwardly of wall 63 to a point shortly forward of wall 72 and is at alevel above the upper ends of conveyor chains 50 to permit the dischargeof dough pieces into the discharge section 56. The trailing section 84of top wall 83 is of reduced width, and a vertical wall 86 depends fromthe trailing edge thereof to wall 59. Front and rear walls 87 extendbetween the corresponding edges of wall section 84 and wall 59 arejoined to front and rear walls 82 by vertical transverse panels 88 whichextend between walls 59 and 83. A rectangular discharge opening 89 isformed in the leading part of wall 59 and is delineated by the loweredges of walls 86 and 87 and the upper edge of wall 63, communicatingwith cage section 56 through an opening 90 between the upper edge ofwall 63 and wall 83, wall 83 being located some distance above thedischarge end of conveyor chains 50. The front wall of cage section 56is defined by a rectangular panel 91 hinged along its bottom edge to theleading edge of wall 81 and hearing at its upper border on a lip 92depending from the leading edge of wall 83 thereby to permit access tocage section 56. It should be noted that suitable slots 93 are providedin the front wall 60 of the cage and in rear wall 87 to provideclearance for heater element arms 22 and shaft 48 respectively and topermit the driving of the latter.

The high-frequency generator assembly 14 comprises a metal housing 94which includes a rectangular base 96, peripheral vertical walls 97 whichare secured to the edges of and project above and below base 96, and atop wall 98. One or more magnetron assemblies are mounted on base 96 andinclude the conventional arrangement of magnets and magnetrons 100, theoutput section of each magnetron 100 projecting through openings in base96 into compartment 80. A blower 101 is associated with each magnetron100 and circulates air around the magnetron 100 to effect the coolingthereof. Magnetrons 100 are connected to a suitable source of energizingcurrent in the known manner. Also mounted on baseplate 96 is a drivemotor 102 connected to a suitable source of power and including avertical drive shaft 103 projecting through an opening in the base 96and having affixed thereto a horizontal metal fan or stirrer 104, theblades of which move in a path directly below magnetrons 100. Fan 101functions to circulate the air and to effect an improved highfrequencyfield distribution in and through compartment 80.

Housing 94 is separably mounted on coupling section 58, base 96 beingprovided with depending peripheral flanges 106 which rest on the upperedges of flanges 73 and 74 and wall 69, and the lower borders of thehousing peripheral walls 97 engaging the outer faces of flanges 73, 74,wings 70 and the upper border of wall 69.

ln employing the apparatus described above in the practice of thepresent improved process as applied to the production of chemicalleavened fried doughnuts, tank 10 is filled with a cooking material,which may be an oil, fat or the like, to a point at about the upperlevel of the advancing flights 42. The control box 21 is adjusted to thedesired temperature to energize heating element 19, thereby to heat theoil to the adjusted regulated temperature. The apparatus is assembled asshown in the drawings and the magnetrons 100, blower 101, drive motor 53and fan motor 102 are energized. Conveyor flights 42 and conveyor belts50 are thus continuously advanced and the flippers 43 synchronouslyrotated, and a high-frequency electromagnetic field is established inthe compartment 80 and is directed into the tank 11 and confined to azone therein defined substantially by the vertical projection of thearea delineated by the lower edges of the partition flange 79, wall 69and walls 71. The doughnut ring forming device 67 is actuated insynchronism with the advancing flights 63 to drop a dough ring throughport 65 into successive pockets between flights 42. The presence ofplate 33 prevents the fresh dough ring from dropping to the bottom oftank 11 and plate 33 is so positioned in relation to the level of thefat such that the entire dough ring is totally immersed for a periodsufficient to form the shape-retention skin before it becomes buoyant.Thereafter, a substantially nonexpandable crust is formed on theunderface of the dough ring as it is advanced by flights 42, with thedough ring floating in the fat. During the initial advance of thefloating dough ring, relatively little expansion is effected. However,as the floating dough ring is advanced to the high-frequency zone, asdefined above, it is rapidly internally heated by the microwave energyand the full expansion of the dough ring is achieved in a highlysuperior and desirable manner, the crusting of the underface of thedough ring effect ing an important contribution to the proper control ofsuch expansion. Upon the dough ring reaching the turning paddle 43, ithas reached substantially its full expansion as effected by thehigh-frequency field and is then inverted and partially submerged in theoil to form a crust on the side previously uppermost, and hence completethe doughnut cooking cycle. The cooked doughnut is advanced by a flight42 onto the conveyor chains 50 where it is carried from the tank 10 anddischarged over the edge thereof into a tray which may be housed in thedischarge section 56. The filled tray may be removed from the dischargesection 56 through the end thereof by opening the door 91.

The temperature of the hot cooking oil, the frying time of the submergedlower portion of the doughnut prior to the high-frequency heatingthereof and the high-frequency heating time depend on the composition ofthe dough or batter and the desired end product and are advantageouslywithin the ranges set forth above. The frying and exposure times may beadjusted by adjusting the speed of the drive shaft 48 either by way ofmotor 53 or otherwise.

As described earlier, the piece of dough may be completely fried on bothsides without necessitating the turning thereof. According to thislatter practice, the paddles 43 are removed and the partition 77 isadvantageously likewise removed. The dough pieces, as they are advancedby the flights 42, first have expansion restricting crusts formed ontheir underfaces and are then exposed to the high-frequency field. lthas been observed that the hot oil is pumped and flows over the upperfaces of the dough pieces exposed to the high-frequency field. However,before any restrictive crust is formed on the dough piece top face, thedough piece fully expands and by the time the dough piece leaves thehigh-frequency field zone, the upper face thereof is fully fried andcrusted by the pumped hot oil.

As one specific example for utilizing the present equipment, a batterofthe following composition was produced in the conventional manner:

30.0 parts water 42.0 parts wheat flour l6.0 parts sucrose 4.0 partsshortening 3.5 parts skim milk solids 1.5 parts yolk solids l.3 partschemical leavening 1.0 parts dextrose 0.7 parts salt The cooking oil wasregulated to a temperature of from 350 to 375 F. and rings of the batterwere formed by the extruding and cutting device 67 and dropped throughport 65 into successive advancing cells or pockets. The advancing rateof the flights 32 was adjusted so that the dough rings were in thecooking oil 10 to 15 seconds to assure proper shaping before enteringthe high-frequency field zone and they were exposed to thehigh-frequency electromagnetic field for from l0 to 20 seconds. Theelectromagnetic field had a wavelength of 12.3 centimeters and themagnetrons delivered 1 6 kilowatts of power. lt should be noted that aradiation confining, swingable metal flap may depend from the lower edgeof the wall 69 into the oil in the tank 11. The dough piece was thenflipped from the high-frequency zone and its opposite face fried for aperiod of about 20 to 40 seconds and then discharged.

The product obtained was a fully cooked and crusted doughnut having aspecific volume greater than 3.6 cc./gram. The cooking process took from50 to 70 seconds, which is approximately one-half to two-thirds of theconventional cooking time.

It is critical under the above conditions to the achievement of optimumproduction of the subject product by the present cooking method that theapplication of the microwave highfrequency electromagnetic energy occur6 to 15 seconds after the dough enters the frying fat to assure theformation of the shape-retention skin of a strength sufficient toappropriately control expansion when the dough piece is subsequentlyexposed to the microwave energy. If this time element is not observed,the product will not shape properly.

Optimum results are obtained for the present formulation when the fryingfat temperature is held between 350 and 375 F. At higher temperatures,the rise time is too fast to permit enough skin formation on the secondside of the doughnut and misshaping occurs when microwaveelectromagnetic energy is applied. At lower temperatures, browning andcrusting are insufficient. On the other hand, a doughnut formulation asdescribed above but containing one-quarter less chemical leavening iscooked to optimum quality in frying fat kept between 350 and 365 F.

In accordance with another example, the batter composition describedabove was employed with the addition of up to 2.0 parts of glycine,lycine or glucosamine or a combination thereof, preferably between 0.5parts and 1.5 parts. The partition 77 and the flippers 43 were removedand the cooking oil was adjusted to a temperature of 350 to 375 F. Doughrings were dropped into the kettle through port 65 and were fried whileadvancing for 6 to 15 seconds before they enter the high-frequency zoneas delineated by the full opening 68. The dough pieces were exposed tothe high-frequency field while being advanced for a period of 30 to 40seconds where they expanded, fully cooked and crusted, and were thendischarged by conveyor chains 50.

It will be noted that in the last described technique of cooking thedoughnut, it was not turned over in the fat but was cooked and crustedon both sides by a surprising and completely unexpected phenomenon. Thephenomenon is characterized by a fountain effect in which the cookingoil is pumped up through the hole in the doughnut and cascades back downover the entire top surface so that the entire doughnut is enveloped inhot fat in the high-frequency field. It has been found that by addingamino acids or Maillard intermediates sufficient coloring of the secondside of the doughnut can be obtained to minimize the difference in colorbetween the two sides that results from one side being submerged in fatfor a longer period of time and subjected to a 4 high temperature sincethe fat pumped up and over the doughnut is somewhat cooled in theprocess.

Employing the above apparatus, there were produced doughnuts ofexceedingly low fat absorptions, 1 ounce per dozen, from a formulationthat would normally absorb 2 or more ounces per dozen. The product has aspecific volume of 3.7 cc./gram and can be produced at the rate of atleast 40 dozen per hour for one cutter in an apparatus 3 feet in length.

As indicated above, the dough pieces may be exposed to thehigh-frequency field in the leading zone following the inversionthereof. This may be accomplished merely by removing only the partition77 and not the flipping assembly. Advantageously, the high-frequencyfield, in the latter case is confined, in addition 'to the trailingzone, to the trailing half of the leading zone.

While there have been described and illustrated preferred embodiments ofthe present invention, it is apparent that numerous alterations,omissions and additions may be made without departing from the spiritand scope thereof.

What we claim is:

l. A cooking apparatus comprising a vessel for containing a cooking oil,means for heating said oil, conveying means for advancing partiallysubmerged articles through said oil from a trailing toward a leadingpart of said vessel, means for depositing pieces of dough into saidtrailing part of said vessel, and means for establishing ahigh-frequency electromagnetic field in the area of said vessel forwardof said trailing part.

2. The apparatus of claim 1, wherein said vessel extends from a trailingend to a leading end and means defining a radiation confiningcompartment disposed forward of said vessel trailing end and having atrailing inlet opening and a leading outlet opening spaced along saidvessel, said highfrequency field being established in said compartmentand said dough depositing means being disposed at a point trailing saidcompartment inlet opening.

3. The apparatus of claim 2, wherein said advancing means comprises anendless chain having an advancing upper run and a plurality of regularlylongitudinally spaced transversely extending flights carried by saidendless chain.

4. The apparatus ofclaim 2, including means positioned forward of saidinlet opening for turning said pieces of dough.

5. The apparatus of claim 5, wherein said turning means is disposedadjacent said outlet opening.

6. The apparatus of claim 2, including radiation shields covering saidvessel leading and trailing said compartment having openings at theirouter ends.

7. Apparatus for forming and cooking a chemically leavened doughnutcomprising a dough ring cutting and extruding device for extruding ashaped, heat-expandable and chemically leavened dough piece from anextrudible dough batch, a fryer including an elongated frying vesseladapted to contain an edible frying medium and arranged in relation tosaid device such that successive extruded pieces are dropped into anedible frying medium contiguous to one end of said frying vessel tototally immerse the same therein, heater means for maintaining saidedible frying medium at a frying temperature wherein said medium is aliquid, successive extruded pieces being totally immersed in said ediblefrying medium to form a shape-retention skin thereon and becomingbuoyant after a period of total immersion and floating to the surface ofthe frying medium, means for conveying successive extruded pieces towardthe other end of said frying vessel with a lower portion of each pieceremaining immersed in said frying medium and an upper portion thereofbeing exposed above the surface of said frying medium and a microwavesource along an intermediate length of said frying vessel arranged tosubject the upper portion of successive extruded pieces to microwaveenergy, said microwave source being of an intensity to heat, expand andat least partially cook the upper portion of successive extruded pieces.

8. Apparatus according to claim 7, including means following saidintermediate length of said frying vessel for turning successiveextruded pieces over to subject the expanded upper portion of successiveextruded pieces to said frying medium along a further length ofsaidfryin vessel.

9. Apparatus for forming and rymg bakery products comprising a fryingtank having an input section, an intermediate section and an outputsection and adapted to contain a liquid cooking medium, means forheating said cooking medium to a frying temperature, a conveyor arrangedwithin said tank for advancing partially submerged bakery products to befried along a conveyor path from said input section through saidintermediate section and to said output section at a prescribed rate, adough ring cutting and extruded device arranged over said input sectionof said frying tank and adapted to drop successive extruded dough piecesfor said bakery product into said input section ofsaid frying tank alongsaid conveyor path, said conveyor being constructed and arranged suchthat successive dough pieces are initially totally submerged in saidcooking medium and then advanced toward said intermediate section in apartially submerged condition, a microwave generator including a cavityand an energy-outlet port arranged to introduce said microwave to saidintermediate section of said frying tank and along said conveyor pathsuch that successive partially submerged dough pieces are exposed tomicrowave energy from said microwave generator for a time determined bysaid prescribed rate and the dimensioning of said energy outlet port anda dough piece-turning mechanism arranged within said frying tank alongsaid conveyor path and following said intermediate section for turningsuccessive dough pieces after exposure to said microwave energy anddelivering the turned dough pieces to said output section.

10. Apparatus according to claim 9, including means along said inputsection of said frying tank arranged to preclude successive dough piecesbeing dropped into said frying tank from coming into contact with thebottom thereof.

11. Apparatus according to claim 9, wherein said means includes a dropplate spaced above the bottom of said frying tank.

12. Apparatus for forming and cooking a chemically leavened bakeryproduct comprising a cutting and extruding device for extruding ashaped, heat-expandable and chemically leavened dough piece from anextrudible dough batch, a fryer including a frying vessel adapted tocontain an edible frying medium and arranged in relation to said devicesuch that successive extruded pieces are dropped into an edible fryingmedium in said frying vessel, heater means for maintaining said ediblefrying medium at a frying temperature wherein said medium is a liquid,means for conveying successive extruded pieces along said frying vesselwith a lower portion of each piece remaining immersed in said fryingmedium and an upper portion being exposed above the surface of saidfrying medium and a microwave source along the length of said fryingvessel arranged to subject the upper portion of successive extrudedpieces to microwave energy, said microwave source being of an intensityto heat, expand and at least partially cook the upper portion ofsuccessive extruded pieces.

13. Apparatus according to claim 12, including means in said fryingvessel and spaced from said microwave source for turning successiveextruded pieces over after exposure to said microwave source tothereafter subject the expanded and cooked upper portion of successiveextruded pieces to said frying medium along a further length of saidfrying vessel.

1. A cooking apparatus comprising a vessel for containing a cooking oil,means for heating said oil, conveying means for advancing partiallysubmerged articles through said oil from a trailing toward a leadingpart of said vessel, means for depositing pieces of dough into saidtrailing part of said vessel, and means for establishing ahigh-frequency electromagnetic field in the area of said vessel forwardof said trailing part.
 2. The apparatus of claim 1, wherein said vesselextends from a trailing end to a leading end and means defining aradiation confining compartment disposed forward of said vessel trailingend and having a trailing inlet opening and a leading outlet openingspaced along said vessel, said high-frequency field being established insaid compartment and said dough depositing means being disposed at apoint trailing said compartment inlet opening.
 3. The apparatus of claim2, wherein said advancing means comprises an endless chain having anadvancing upper run and a plurality of regularly longitudinally spacedtransversely extending flights carried by said endless chain.
 4. Theapparatus of claim 2, including means positioned forward of said inletopening for turning said pieces of dough.
 5. The apparatus of claim 5,wherein said turning means is disposed adjacent said outlet opening. 6.The apparatus of claim 2, including radiation shields covering saidvessel leading and trailing said compartment having openings at theirouter ends.
 7. Apparatus for forming and cooking a chemically leaveneddoughnut comprising a dough ring cutting and extruding device forextruding a shaped, heat-expandable and chemically leavened dough piecefrom an extrudible dough batch, a fryer including an elongated fryingvessel adapted to contain an edible frying medium and arranged inrelation to said device such that successive extruded pieces are droppedinto an edible frying medium contiguous to one end of said frying vesselto totally immerse the same therein, heater means for maintaining saidedible frying medium at a frying temperature wherein said medium is aliquid, successive extruded pieces being totally immersed in said ediblefrying medium to form a shape-retention skin thereon and becomingbuoyant after a period of total immersion and floating to the surface ofthe frying medium, means for conveying successive extruded pieces towardthe other end of said frying vessel with a lower portion of each pieceremaining immersed in said frying medium and an upper portion thereofbeing exposed above the surface of said frying medium and a microwavesource along an intermediate length of said frying vessel arranged tosubject the upper portion of successive extruded pieces to microwaveenergy, said microwave source being of an intensity to heat, expand andat least partially cook the upper portion of successive extruded pieces.8. Apparatus according to claim 7, including means following saidintermediate length of said frying vessel for turning successiveextruded pieces over to subject the expanded upper portion of successiveextruded pieces to said frying medium along a further length of saidfrying vessel.
 9. Apparatus for forming and frying bakery productscomprising a frying tank having an input section, an intermediatesection and an output section and adapted to contain a liquid cookingmedium, means for heating said cooking medium to a frying temperature, aconveyor arranged within said tank for advancing partially submergedbakery products to be fried along a conveyor path from said inputsection through said intermediate section and to said output section ata prescribed rate, a dough ring cutting and extruded device arrangedover said input section of said frying tank and adapted to dropsuccessive extruded dough pieces for said bakery product into said inputsection of said frying tank along said conveyor path, said conveyorbeing constructed and arranged such that successive dough pieces areinitially totally submerged in said cooking medium and then advancedtoward said intermediate section in a partially submerged condition, amicrowave generator including a cavity and an energy-outlet portarranged to introduce said microwave to said intermediate section ofsaid frying tank and along said conveyor path such that successivepartially submerged dough pieces are exposed to microwave energy fromsaid microwave generator for a time determined by said prescribed rateand the dimensioning of said energy outlet port and a doughpiece-turning mechanism arranged within said frying tank along saidconveyor path and following said intermediate section for turningsuccessive dough pieces after exposure to said microwave energy anddelivering the turned dough pieces to said output section.
 10. Apparatusaccording to claim 9, including means along said input section of saidfrying tank arranged to preclude successive dough pieces being droppedinto said frying tank from coming into contact with the bottom thereof.11. Apparatus according to claim 9, wherein said means includes a dropplate spaced above the bottom of said frying tank.
 12. Apparatus forforming and cooking a chemically leavened bakery product comprising acutting and extruding device for extruding a shaped, heat-expandable andchemically leavened dough piece from an extrudible dough batch, a fryerincluding a frying vessel adapted to contain an edible frying medium andarranged in relation to said device such that successive extruded piecesare dropped into an edible frying medium in said frying vessel, heatermeans for maintaining said edible frying medium at a frying temperaturewherein said medium is a liquid, means for conveying successive extrudedpieces along said frying vessel with a lower portion of each pieceremaining immersed in said frying medium and an upper portion beingexposed above the surface of said frying medium and a microwave sourcealong the length of said frying vessel arranged to subject the upperportion of successive extruded pieces to microwave energy, saidmicrowave source being of an intensity to heat, expand and at leastpartially cook the upper portion of successive extruded pieces. 13.Apparatus according to claim 12, including means in said frying vesseland spaced from said microwave source for turning successive extrudedpieces over after exposure to said microwave source to thereaftersubject the expanded and cooked upper portion of successive extrudedpieces to said frying medium along a further length of said fryingvessel.